Human powered watercraft tend to have low drive train efficiency. Current designs generally have comparatively high friction. The commonly used rudder used in combination with a propeller contributes to viscous drag. Propulsion systems not using propellers generally compromise steering and induce a wide turning radius, which may be a factor in safe navigation. Many currently used propulsion and steering controls project far below the waterline, which can hamper, or even prevent propulsion in shallow water. Accordingly, engineering challenges remain in designing human powered watercraft that are highly efficient as well as highly maneuverable.